In wireless communications systems, communications devices communicate with a centrally located base station within a cell. The wireless communications system may be a CDMA2000 or GSM communications system, for example. The mobile communications device is typically a hand-held device, such as a cell telephone, for example. Communications devices also communicate with access points by making use of wireless local area network (WLAN) protocols. For example, the communications device may be a PCMCIA card (Personal Computer Memory Card International Association) or a USB adaptor compatible with the 802.11 standards.
In some embodiments, the antenna protrudes from the housing or enclosure of the communications device. The antenna may be a protruding monopole or dipole antenna, for example. A monopole or dipole antenna is limited to a fixed pattern, such as an omni-directional antenna pattern.
Another type of antenna used with communications devices is a switched beam antenna. A switched beam antenna system generates a plurality of antenna beams including an omni-directional antenna beam and one or more directional antenna beams. Directional antenna beams provide higher antenna gains for advantageously increasing the communications range of the communications device and for also increasing network throughput. A switched beam antenna is also known as a smart antenna or an adaptive antenna array.
U.S. Pat. No. 6,876,331 discloses a smart antenna for a communications device, such as a cell phone. This patent is assigned to the current assignee of the present invention, and is incorporated herein by reference in its entirety. In particular, the smart antenna includes an active antenna element and a plurality of passive antenna elements protruding from the housing of the cell phone. A ground plane is adjacent the active and passive antenna elements.
The overall height of the smart antenna is determined by the height of the active and passive antenna elements and the height of the corresponding ground plane. This in turn affects the overall height of the wireless communications device carrying the smart antenna. As technology reduces the size of the wireless communications devices, there is a demand to provide a more compact smart antenna.